The present invention relates generally to control systems, and more particularly to model predictive control employing novel techniques for optimizing the temperature of cook flash steam used in a distillation process.
A secondary distillation tower, such as a side stripper column in biofuels production plants, may be used to separate water from biofuels, such as ethanol. This secondary distillation tower may have more than one heat source, such as waste heat from a process unit known as the cook tube. In the cook tube, the biofuels feedstock may be heated to improve solubility of the feedstock mixture with water and enzymes. In addition, the cook tube may sterilize the biofuels and reduce bacterial infection of the biofuel feedstock to fermentation.
In a cooking and milling section of the biofuels production plant, the heated biofuels feedstock, after exiting the cook tube, may be sent through a flash vessel, where excess heat may be flashed and used as a source of heat in the secondary distillation tower. However, elevated cook flash may generate excess amounts of steam flashed to the side stripper column, making separation of water/ethanol a more costly process. In addition to this heat source, the side stripper column may be directly injected with steam from a boiler system. However, ensuring the right amount of steam into the side stripper is an important economic cost optimization problem.